Input Box Allow To Input The Column Number

I want to create an input box that will allow you to input the column number it should start in... so instead of it being fixed at A, you can choose column B, C, D all the way to the end if you like.

Sub SplitSheetsNoDelete1()
Application.ScreenUpdating = False
Application.DisplayAlerts = False
Dim Lmainsheet As String
Dim Lrow As Integer
Dim lcontinue As Boolean

Dim LColamaster As String
Dim lcolatest As String

'Retrieve name of sheet that contains the data
Lmainsheet = ActiveSheet.Name

'Initialize variables
lcontinue = True
Lrow = 2.....................................